This may be completely uninformed, but it seems that the boot-floppies package in potato won't install simply because the dependency on newt0.25 and newt0.25-dev can't be fulfilled since the version available is greater than .25. I'm not sure if this can be done -- but why can't boot-floppies accept versions of newt >= 0.25 -- since .30 is available in potato.
seemed odd to me anyway... bye -abr